1. Field of the Invention
The present invention relates to a multidirectional input device and more particularly to a multidirectional input device wherein, by tilting an operating shaft, a variable condenser is operated and an operational direction of the operating shaft can be inputted.
2. Description of the Prior Art
A multidirectional input device has heretofore been used as a controller for a computer game machine or as a balance controller for four speakers disposed in front, rear, right and left positions of, for example, a four-channel home theater system or a car audio system.
A conventional multidirectional input device will be described below with reference to FIGS. 5 and 6, of which FIG. 5 is a longitudinal sectional view of the conventional multidirectional input device and FIG. 6 is a transverse sectional view thereof.
As shown in FIGS. 5 and 6, a support portion 33a of an operating lever 33 is supported by an upper wall 31a of a casing 31 through a swivel bearing 32, the operating lever 33 being tiltable at a predetermined angle in an arbitrary direction.
A generally U-shaped first arm 34 and a generally U-shaped second arm 35 are disposed substantially crosswise in the interior of the casing 31, the first arm 34 being rotatable about Y axis which extends in Y axis direction (the vertical direction in FIG. 6) and the second arm 35 rotatable about X axis which extends in X axis direction (the right and left direction in FIG. 6). More specifically, one end portion of the first arm 34 is supported pivotably with a pin 36 which extends through a side wall 31b of the casing 31, while an opposite end portion of the first arm 34 is fixed to an input shaft 38 which is rotatable at a predetermined angle, the input shaft 38 projecting outwards from a first variable resistor 37 and passing through a side wall 31b of the casing 31, the first variable resistor 37 being attached to an outer surface side of the casing side wall 31b. 
As to the second arm 35, one end portion thereof is supported pivotably with a pin 39 which extends through a side wall 31b of the casing 31, while an opposite end portion of the second arm 35 is fixed to an input shaft 41 which is rotatable at a predetermined angle, the input shaft 41 projecting outwards from a second variable resistor 40 and passing through a side wall 31b of the casing 31, the second variable resistor 40 being attached to an outery surface side of the casing side wall 31b. 
Longitudinally extending elongated holes 42 and 43 are formed in the first and second arms 34, 35, respectively. A lower end portion of the operating lever 33 extends through both elongated holes 42 and 43. Therefore, when the operating lever 33 is tilted in an arbitrary direction, the input shaft 38 of the first variable resistor 37 rotates in accordance with the tilt angle in the X-axis direction of the operating lever 33 and the input shaft 41 of the second variable resistor 40 rotates in accordance with the tilt angle in the Y-axis direction of the operating lever 33.
Though not shown, the first and second variable resistors 37, 40 are each provided with an insulating substrate having printed carbon resistor and electrode terminals, a slider adapted to slide on the carbon resistor, terminals connected to the electrode terminals, and a housing which houses those components therein.
An amplifier substrate 45 is attached to an outer surface side of a side wall 31b of the casing 31 through plural brackets 44 formed of an insulator, and an amplifier circuit (not shown) constituted by an integrated circuit for example is mounted on the amplifier substrate 45.
The operation of this conventional multidirectional input device will be described below.
First, when the operating lever 33 is tilted in an arbitrary direction, the first arm 34 turns about the pin 36 and at the same time the second arm 35 turns about the pin 39. The turning angle of the first arm 34 corresponds to the tilt angle in the X axis direction of the operating lever 33 and the input shaft 38 of the first resistor 37 rotates together with the first arm 34. Consequently, the resistance value of the first variable resistor 37 varies in accordance with the tilt angle in the X axis direction of the operating lever 33.
Likewise, the turning angle of the second arm 35 corresponds to the tilt angle in the Y axis direction of the operating lever 33 and the input shaft 41 of the second variable resistor 40 rotates together with the second arm 35. Consequently, the resistance value of the second variable resistor 40 varies in accordance with the tilt angle in the Y axis direction of the operating lever 33.
That is, X and Y components of inclination of the operating lever 33 are detected on the basis of changes in resistance value of the first and second variable resistors 37, 40, whereby, for example, it is possible to control the motion of characters in a computer game machine or control the balance of four speakers disposed in front, rear, right and left positions of a four-channel home theater system or a car audio system.
In the conventional multidirectional input device, as described above, the resistance values of the first and second variable resistors 37, 40 vary upon tilting of the operating lever 33 in an arbitrary direction. However, since the first and second variable resistors 37 and 40 are each provided with an insulating substrate having a carbon resistor and electrode terminals, a slider, terminals, and a housing, the number of components is large and hence the number of assembling steps increases, that is, the cost of each variable resistor becomes high, thus giving rise to the problem that the multidirectional input device becomes expensive.
The present invention has been accomplished for solving the above-mentioned problems and it is an object of the invention to provide a multidirectional input device small in the number of components, superior in assemblability and less expensive.
According to the present invention, in the first aspect thereof, there is provided a multidirectional input device comprising a frame having an upper wall, a printed wiring board which closes a lower portion of the frame and which has a fixed electrode portion, and an operating shaft supported by the frame and adapted to be tilted with respect to the upper wall of the frame, wherein a movable electrode portion is attached to the operating shaft in an opposed relation to the fixed electrode portion and is moved by operation of the operating shaft to change an opposition area between the movable electrode portion and the fixed electrode portion, and a change in capacitance between both electrode portions is detected to obtain an operational direction of the operating shaft.
In the second aspect of the present invention there is provided, in combination with the above first aspect, a multidirectional input device wherein an interlocking member having a longitudinal slot is mounted bridgewise in the interior of the frame, the operating shaft is inserted into the slot and is supported by the interlocking member, the operating shaft can be tilted in both the longitudinal direction of the slot and a direction intersecting the longitudinal direction of the slot, and when the operating shaft is tilted in the longitudinal direction of the slot, only the operating shaft rotates, while when the operating shaft is tilted in the direction intersecting the longitudinal direction of the slot, the interlocking member rotates, centered on the longitudinal direction, with rotation of the operating shaft.
In the third aspect of the present invention there is provided, in combination with the above first aspect, a multidirectional input device wherein a slide member is disposed on an upper surface of the printed wiring board so that it can be moved along the upper surface of the printed wiring board by a tilting motion of the operating shaft, and the movable electrode portion is fixed to the slide member and is moved in parallel with the fixed electrode portion by a tilting motion of the operating shaft.
In the fourth aspect of the present invention there is provided, in combination with the above first aspect, a multidirectional input device wherein the fixed electrode portion is formed by a conductor pattern on an upper surface of the printed wiring board.
In the fifth aspect of the present invention there is provided, in combination with the above first aspect, a multidirectional input device wherein the fixed electrode portion has an earth electrode and a first fixed electrode adjacent to the earth electrode, the earth electrode and the first fixed electrode being opposed to the movable electrode portion, and a change in capacitance between the fixed electrode portion and the movable electrode portion caused by movement of the movable electrode portion is detected through the earth electrode opposed to the movable electrode portion.
In the sixth aspect of the present invention there is provided, in combination with the above first aspect, a multidirectional input device wherein the fixed electrode portion comprises four earth electrodes arranged crosswise and first, second, third and fourth fixed electrodes each disposed between adjacent the earth electrodes, the fixed electrode portion is formed in a generally circular shape by the earth electrodes and the first to fourth fixed electrodes, the earth electrodes and the first to fourth fixed electrodes being opposed to the movable electrode portion which is formed in a circular shape, changes in capacitance between each of the first to fourth fixed electrodes and the movable electrode portion caused by movement of the movable electrode portion are detected through the earth electrodes opposed to the movable electrode portion, a displacement in X direction of the operating shaft is detected by calculating a difference between the sum of a capacitance value between the first fixed electrode and the movable electrode portion and a capacitance value between the second fixed electrode and the movable electrode portion and the sum of a capacitance value between the third fixed electrode and the movable electrode portion and a capacitance value between the fourth fixed electrode and the movable electrode portion, a displacement in Y direction of the operating shaft is detected by calculating a difference between the sum of a capacitance value between the first fixed electrode and the movable electrode portion and a capacitance value between the fourth fixed electrode and the movable electrode portion and the sum of a capacitance value between the second fixed-electrode and the movable electrode portion and a capacitance value between the third fixed electrode and the movable electrode portion, and a tilting direction of the operating shaft is detected from the calculation results of the displacements in X and Y directions.
In the seventh aspect of the present invention there is provided, in combination with the above first aspect, a multidirectional input device wherein an insulating film is disposed between the movable electrode portion and the fixed electrode portion, and the movable electrode portion slides in contact with an upper surface of the insulating film.
In the eighth aspect of the present invention there is provided, in combination with the above seventh aspect, a multidirectional input device wherein the insulating film is disposed on the printed wiring board so as to cover the fixed electrode portion and is sandwiched between the printed wiring board and the lower portion of the frame.
In the ninth aspect of the present invention there is provided a multidirectional input device comprising a first interlocking member having a first longitudinal slot, a second interlocking member disposed in a direction orthogonal to the longitudinal direction of the first interlocking member and having a second longitudinal slot, a frame within which the first and second interlocking members are bridgewise mounted rotatably, a printed wiring board which closes a lower portion of the frame, and an operating shaft inserted into the first and second slots, supported by the first and second interlocking members and adapted to tilt in the longitudinal directions of the first and second slots, wherein movable electrode portions are fixed to the first and second interlocking members respectively, fixed electrode portions are fixed to the printed wiring board in an opposed relation to the movable electrode portions, the first and second interlocking members are rotated, centered on the longitudinal directions of the first and second slots respectively, by operation of the operating shaft, thereby rotating the movable electrode portions to change an opposition area between each movable electrode portion and each fixed electrode portion, and a change in capacitance between each movable electrode portion and each fixed electrode portion is detected to obtain an operational direction of the operating shaft.
In the tenth aspect of the present invention there is provided, in combination with the ninth aspect, a multidirectional input device wherein one end portions of the first and second interlocking members project outwards from the frame, the movable electrode portions are fixed to the end portions respectively, and the fixed electrode portions are disposed outside the frame.
In the eleventh aspect of the present invention there is provided, in combination with the ninth aspect, a multidirectional input device wherein the fixed electrode portions each comprise an earth electrode and a first fixed electrode adjacent to the earth electrode, the earth electrode and the first fixed electrode being opposed to the associated movable electrode portion, and a change in capacitance between the first fixed electrode and the associated movable electrode portion caused by rotation of the movable electrode portion is detected through the earth electrode opposed to the movable electrode portion.
In the twelfth aspect of the present invention there is provided, in combination with the ninth aspect, a multidirectional input device wherein the fixed electrode portions each comprise an earth electrode and a pair of first and second fixed electrodes adjacent to both sides of the earth electrode, the earth electrode and the first and second fixed electrodes being opposed to the associated movable electrode portion, an opposition area between the first fixed electrode and the associated movable electrode portion and an opposition area between the second fixed electrode and the movable electrode portion are equal to each other when the operating shaft is in a position perpendicular to the printed wiring board, and a change in capacitance between the first fixed electrode and the associated movable electrode portion and a change in capacitance between the second fixed electrode and the movable electrode portion both caused by rotation of the movable electrode portion are detected through the earth electrode opposed to the movable electrode portion.
In the thirteenth aspect of the present invention there is provided, in combination with the ninth aspect, a multidirectional input device wherein the movable electrode portions and the fixed electrode portions are respectively formed by metallic plates, one end portions of the metallic plates serving as the movable electrode portions are press-fitted into slits formed in the first and second interlocking members respectively, and the metallic plates serving as the fixed electrode portions- are soldered directly to the printed wiring board.